1. Field of the Invention
The present invention generally relates to an injection-locked frequency divider, and more particularly, to a differential injection-locked frequency divider.
2. Description of Related Art
Frequency dividers are widely used in hybrid integrated circuits (IC). For example, frequency dividers are critical components for multiplexers, phase-locked loops (PLL), and frequency synthesizers. Currently, responsive to the demands of consumers, and the variations of system technologies, injection-locked frequency dividers, which are more suitable for operations of high speed systems, have become outstanding among variety of frequency dividers. Typically, a present injection-locked frequency divider usually input signals from only a single terminal.
FIG. 1 is a circuit diagram illustrating a conventional injection-locked frequency divider. Referencing to FIG. 1, a conventional injection-locked frequency divider 100 includes an oscillator 110 that is a Colpitts oscillator and a signal injection unit 120. The signal injection unit 120 receives an injection signal SIN1 by a single terminal. The oscillator 110 adjusts an oscillation frequency thereof via a reactance control signal SIP1. When an oscillation frequency of the oscillator 110 approaches to one third of frequency of the injection signal SIN1, the conventional injection-locked frequency divider 100 locks and generates a dividing signal SDI1. Such an injection-locked frequency divider 100 having such an injection type is called a direct injection divider. The signal injection unit 120 includes transistors M01, and M02. Source/drain terminals of the transistors M01 and M02 are equipotential, and therefore consume two sets of source/drain currents. As such, such kinds of circuits usually consume a lot of power when being operated at a high frequency, and will configure ring oscillation frequency dividers when applied in ordinary digital circuits so that the frequency thereof would be restricted.
Therefore, in practical operation, a conventional injection-locked frequency divider typically has the disadvantages of smaller locking range and large power consumption. In other words, such a restricted conventional injection-locked frequency divider can not be widely applied in so many kinds of hybrid ICs.